/****************************************************************************
 *
 * ftcache.h
 *
 *   FreeType Cache subsystem (specification).
 *
 * Copyright (C) 1996-2019 by
 * David Turner, Robert Wilhelm, and Werner Lemberg.
 *
 * This file is part of the FreeType project, and may only be used,
 * modified, and distributed under the terms of the FreeType project
 * license, LICENSE.TXT.  By continuing to use, modify, or distribute
 * this file you indicate that you have read the license and
 * understand and accept it fully.
 *
 */

#ifndef FTCACHE_H_
#define FTCACHE_H_

#include <ft2build.h>
#include FT_GLYPH_H

FT_BEGIN_HEADER

/**************************************************************************
 *
 * @section:
 *   cache_subsystem
 *
 * @title:
 *   Cache Sub-System
 *
 * @abstract:
 *   How to cache face, size, and glyph data with FreeType~2.
 *
 * @description:
 *   This section describes the FreeType~2 cache sub-system, which is used
 *   to limit the number of concurrently opened @FT_Face and @FT_Size
 *   objects, as well as caching information like character maps and glyph
 *   images while limiting their maximum memory usage.
 *
 *   Note that all types and functions begin with the `FTC_` prefix.
 *
 *   The cache is highly portable and thus doesn't know anything about the
 *   fonts installed on your system, or how to access them.  This implies
 *   the following scheme:
 *
 *   First, available or installed font faces are uniquely identified by
 *   @FTC_FaceID values, provided to the cache by the client.  Note that
 *   the cache only stores and compares these values, and doesn't try to
 *   interpret them in any way.
 *
 *   Second, the cache calls, only when needed, a client-provided function
 *   to convert an @FTC_FaceID into a new @FT_Face object.  The latter is
 *   then completely managed by the cache, including its termination
 *   through @FT_Done_Face.  To monitor termination of face objects, the
 *   finalizer callback in the `generic` field of the @FT_Face object can
 *   be used, which might also be used to store the @FTC_FaceID of the
 *   face.
 *
 *   Clients are free to map face IDs to anything else.  The most simple
 *   usage is to associate them to a (pathname,face_index) pair that is
 *   used to call @FT_New_Face.  However, more complex schemes are also
 *   possible.
 *
 *   Note that for the cache to work correctly, the face ID values must be
 *   **persistent**, which means that the contents they point to should not
 *   change at runtime, or that their value should not become invalid.
 *
 *   If this is unavoidable (e.g., when a font is uninstalled at runtime),
 *   you should call @FTC_Manager_RemoveFaceID as soon as possible, to let
 *   the cache get rid of any references to the old @FTC_FaceID it may keep
 *   internally.  Failure to do so will lead to incorrect behaviour or even
 *   crashes.
 *
 *   To use the cache, start with calling @FTC_Manager_New to create a new
 *   @FTC_Manager object, which models a single cache instance.  You can
 *   then look up @FT_Face and @FT_Size objects with
 *   @FTC_Manager_LookupFace and @FTC_Manager_LookupSize, respectively.
 *
 *   If you want to use the charmap caching, call @FTC_CMapCache_New, then
 *   later use @FTC_CMapCache_Lookup to perform the equivalent of
 *   @FT_Get_Char_Index, only much faster.
 *
 *   If you want to use the @FT_Glyph caching, call @FTC_ImageCache, then
 *   later use @FTC_ImageCache_Lookup to retrieve the corresponding
 *   @FT_Glyph objects from the cache.
 *
 *   If you need lots of small bitmaps, it is much more memory efficient to
 *   call @FTC_SBitCache_New followed by @FTC_SBitCache_Lookup.  This
 *   returns @FTC_SBitRec structures, which are used to store small bitmaps
 *   directly.  (A small bitmap is one whose metrics and dimensions all fit
 *   into 8-bit integers).
 *
 *   We hope to also provide a kerning cache in the near future.
 *
 *
 * @order:
 *   FTC_Manager
 *   FTC_FaceID
 *   FTC_Face_Requester
 *
 *   FTC_Manager_New
 *   FTC_Manager_Reset
 *   FTC_Manager_Done
 *   FTC_Manager_LookupFace
 *   FTC_Manager_LookupSize
 *   FTC_Manager_RemoveFaceID
 *
 *   FTC_Node
 *   FTC_Node_Unref
 *
 *   FTC_ImageCache
 *   FTC_ImageCache_New
 *   FTC_ImageCache_Lookup
 *
 *   FTC_SBit
 *   FTC_SBitCache
 *   FTC_SBitCache_New
 *   FTC_SBitCache_Lookup
 *
 *   FTC_CMapCache
 *   FTC_CMapCache_New
 *   FTC_CMapCache_Lookup
 *
 *************************************************************************/

/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*****                                                               *****/
/*****                    BASIC TYPE DEFINITIONS                     *****/
/*****                                                               *****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/

/**************************************************************************
 *
 * @type:
 *   FTC_FaceID
 *
 * @description:
 *   An opaque pointer type that is used to identity face objects.  The
 *   contents of such objects is application-dependent.
 *
 *   These pointers are typically used to point to a user-defined structure
 *   containing a font file path, and face index.
 *
 * @note:
 *   Never use `NULL` as a valid @FTC_FaceID.
 *
 *   Face IDs are passed by the client to the cache manager that calls,
 *   when needed, the @FTC_Face_Requester to translate them into new
 *   @FT_Face objects.
 *
 *   If the content of a given face ID changes at runtime, or if the value
 *   becomes invalid (e.g., when uninstalling a font), you should
 *   immediately call @FTC_Manager_RemoveFaceID before any other cache
 *   function.
 *
 *   Failure to do so will result in incorrect behaviour or even memory
 *   leaks and crashes.
 */
typedef FT_Pointer FTC_FaceID;

/**************************************************************************
 *
 * @functype:
 *   FTC_Face_Requester
 *
 * @description:
 *   A callback function provided by client applications.  It is used by
 *   the cache manager to translate a given @FTC_FaceID into a new valid
 *   @FT_Face object, on demand.
 *
 * @input:
 *   face_id ::
 *     The face ID to resolve.
 *
 *   library ::
 *     A handle to a FreeType library object.
 *
 *   req_data ::
 *     Application-provided request data (see note below).
 *
 * @output:
 *   aface ::
 *     A new @FT_Face handle.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   The third parameter `req_data` is the same as the one passed by the
 *   client when @FTC_Manager_New is called.
 *
 *   The face requester should not perform funny things on the returned
 *   face object, like creating a new @FT_Size for it, or setting a
 *   transformation through @FT_Set_Transform!
 */
typedef FT_Error (*FTC_Face_Requester)(FTC_FaceID face_id, FT_Library library, FT_Pointer req_data,
                                       FT_Face *aface);

/* */

/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*****                                                               *****/
/*****                      CACHE MANAGER OBJECT                     *****/
/*****                                                               *****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/

/**************************************************************************
 *
 * @type:
 *   FTC_Manager
 *
 * @description:
 *   This object corresponds to one instance of the cache-subsystem.  It is
 *   used to cache one or more @FT_Face objects, along with corresponding
 *   @FT_Size objects.
 *
 *   The manager intentionally limits the total number of opened @FT_Face
 *   and @FT_Size objects to control memory usage.  See the `max_faces` and
 *   `max_sizes` parameters of @FTC_Manager_New.
 *
 *   The manager is also used to cache 'nodes' of various types while
 *   limiting their total memory usage.
 *
 *   All limitations are enforced by keeping lists of managed objects in
 *   most-recently-used order, and flushing old nodes to make room for new
 *   ones.
 */
typedef struct FTC_ManagerRec_ *FTC_Manager;

/**************************************************************************
 *
 * @type:
 *   FTC_Node
 *
 * @description:
 *   An opaque handle to a cache node object.  Each cache node is
 *   reference-counted.  A node with a count of~0 might be flushed out of a
 *   full cache whenever a lookup request is performed.
 *
 *   If you look up nodes, you have the ability to 'acquire' them, i.e., to
 *   increment their reference count.  This will prevent the node from
 *   being flushed out of the cache until you explicitly 'release' it (see
 *   @FTC_Node_Unref).
 *
 *   See also @FTC_SBitCache_Lookup and @FTC_ImageCache_Lookup.
 */
typedef struct FTC_NodeRec_ *FTC_Node;

/**************************************************************************
 *
 * @function:
 *   FTC_Manager_New
 *
 * @description:
 *   Create a new cache manager.
 *
 * @input:
 *   library ::
 *     The parent FreeType library handle to use.
 *
 *   max_faces ::
 *     Maximum number of opened @FT_Face objects managed by this cache
 *     instance.  Use~0 for defaults.
 *
 *   max_sizes ::
 *     Maximum number of opened @FT_Size objects managed by this cache
 *     instance.  Use~0 for defaults.
 *
 *   max_bytes ::
 *     Maximum number of bytes to use for cached data nodes.  Use~0 for
 *     defaults.  Note that this value does not account for managed
 *     @FT_Face and @FT_Size objects.
 *
 *   requester ::
 *     An application-provided callback used to translate face IDs into
 *     real @FT_Face objects.
 *
 *   req_data ::
 *     A generic pointer that is passed to the requester each time it is
 *     called (see @FTC_Face_Requester).
 *
 * @output:
 *   amanager ::
 *     A handle to a new manager object.  0~in case of failure.
 *
 * @return:
 *   FreeType error code.  0~means success.
 */
FT_EXPORT(FT_Error)
FTC_Manager_New(FT_Library library, FT_UInt max_faces, FT_UInt max_sizes, FT_ULong max_bytes,
                FTC_Face_Requester requester, FT_Pointer req_data, FTC_Manager *amanager);

/**************************************************************************
 *
 * @function:
 *   FTC_Manager_Reset
 *
 * @description:
 *   Empty a given cache manager.  This simply gets rid of all the
 *   currently cached @FT_Face and @FT_Size objects within the manager.
 *
 * @inout:
 *   manager ::
 *     A handle to the manager.
 */
FT_EXPORT(void)
FTC_Manager_Reset(FTC_Manager manager);

/**************************************************************************
 *
 * @function:
 *   FTC_Manager_Done
 *
 * @description:
 *   Destroy a given manager after emptying it.
 *
 * @input:
 *   manager ::
 *     A handle to the target cache manager object.
 */
FT_EXPORT(void)
FTC_Manager_Done(FTC_Manager manager);

/**************************************************************************
 *
 * @function:
 *   FTC_Manager_LookupFace
 *
 * @description:
 *   Retrieve the @FT_Face object that corresponds to a given face ID
 *   through a cache manager.
 *
 * @input:
 *   manager ::
 *     A handle to the cache manager.
 *
 *   face_id ::
 *     The ID of the face object.
 *
 * @output:
 *   aface ::
 *     A handle to the face object.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   The returned @FT_Face object is always owned by the manager.  You
 *   should never try to discard it yourself.
 *
 *   The @FT_Face object doesn't necessarily have a current size object
 *   (i.e., face->size can be~0).  If you need a specific 'font size', use
 *   @FTC_Manager_LookupSize instead.
 *
 *   Never change the face's transformation matrix (i.e., never call the
 *   @FT_Set_Transform function) on a returned face!  If you need to
 *   transform glyphs, do it yourself after glyph loading.
 *
 *   When you perform a lookup, out-of-memory errors are detected _within_
 *   the lookup and force incremental flushes of the cache until enough
 *   memory is released for the lookup to succeed.
 *
 *   If a lookup fails with `FT_Err_Out_Of_Memory` the cache has already
 *   been completely flushed, and still no memory was available for the
 *   operation.
 */
FT_EXPORT(FT_Error)
FTC_Manager_LookupFace(FTC_Manager manager, FTC_FaceID face_id, FT_Face *aface);

/**************************************************************************
 *
 * @struct:
 *   FTC_ScalerRec
 *
 * @description:
 *   A structure used to describe a given character size in either pixels
 *   or points to the cache manager.  See @FTC_Manager_LookupSize.
 *
 * @fields:
 *   face_id ::
 *     The source face ID.
 *
 *   width ::
 *     The character width.
 *
 *   height ::
 *     The character height.
 *
 *   pixel ::
 *     A Boolean.  If 1, the `width` and `height` fields are interpreted as
 *     integer pixel character sizes.  Otherwise, they are expressed as
 *     1/64th of points.
 *
 *   x_res ::
 *     Only used when `pixel` is value~0 to indicate the horizontal
 *     resolution in dpi.
 *
 *   y_res ::
 *     Only used when `pixel` is value~0 to indicate the vertical
 *     resolution in dpi.
 *
 * @note:
 *   This type is mainly used to retrieve @FT_Size objects through the
 *   cache manager.
 */
typedef struct FTC_ScalerRec_ {
	FTC_FaceID face_id;
	FT_UInt width;
	FT_UInt height;
	FT_Int pixel;
	FT_UInt x_res;
	FT_UInt y_res;

} FTC_ScalerRec;

/**************************************************************************
 *
 * @struct:
 *   FTC_Scaler
 *
 * @description:
 *   A handle to an @FTC_ScalerRec structure.
 */
typedef struct FTC_ScalerRec_ *FTC_Scaler;

/**************************************************************************
 *
 * @function:
 *   FTC_Manager_LookupSize
 *
 * @description:
 *   Retrieve the @FT_Size object that corresponds to a given
 *   @FTC_ScalerRec pointer through a cache manager.
 *
 * @input:
 *   manager ::
 *     A handle to the cache manager.
 *
 *   scaler ::
 *     A scaler handle.
 *
 * @output:
 *   asize ::
 *     A handle to the size object.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   The returned @FT_Size object is always owned by the manager.  You
 *   should never try to discard it by yourself.
 *
 *   You can access the parent @FT_Face object simply as `size->face` if
 *   you need it.  Note that this object is also owned by the manager.
 *
 * @note:
 *   When you perform a lookup, out-of-memory errors are detected _within_
 *   the lookup and force incremental flushes of the cache until enough
 *   memory is released for the lookup to succeed.
 *
 *   If a lookup fails with `FT_Err_Out_Of_Memory` the cache has already
 *   been completely flushed, and still no memory is available for the
 *   operation.
 */
FT_EXPORT(FT_Error)
FTC_Manager_LookupSize(FTC_Manager manager, FTC_Scaler scaler, FT_Size *asize);

/**************************************************************************
 *
 * @function:
 *   FTC_Node_Unref
 *
 * @description:
 *   Decrement a cache node's internal reference count.  When the count
 *   reaches 0, it is not destroyed but becomes eligible for subsequent
 *   cache flushes.
 *
 * @input:
 *   node ::
 *     The cache node handle.
 *
 *   manager ::
 *     The cache manager handle.
 */
FT_EXPORT(void)
FTC_Node_Unref(FTC_Node node, FTC_Manager manager);

/**************************************************************************
 *
 * @function:
 *   FTC_Manager_RemoveFaceID
 *
 * @description:
 *   A special function used to indicate to the cache manager that a given
 *   @FTC_FaceID is no longer valid, either because its content changed, or
 *   because it was deallocated or uninstalled.
 *
 * @input:
 *   manager ::
 *     The cache manager handle.
 *
 *   face_id ::
 *     The @FTC_FaceID to be removed.
 *
 * @note:
 *   This function flushes all nodes from the cache corresponding to this
 *   `face_id`, with the exception of nodes with a non-null reference
 *   count.
 *
 *   Such nodes are however modified internally so as to never appear in
 *   later lookups with the same `face_id` value, and to be immediately
 *   destroyed when released by all their users.
 *
 */
FT_EXPORT(void)
FTC_Manager_RemoveFaceID(FTC_Manager manager, FTC_FaceID face_id);

/**************************************************************************
 *
 * @type:
 *   FTC_CMapCache
 *
 * @description:
 *   An opaque handle used to model a charmap cache.  This cache is to hold
 *   character codes -> glyph indices mappings.
 *
 */
typedef struct FTC_CMapCacheRec_ *FTC_CMapCache;

/**************************************************************************
 *
 * @function:
 *   FTC_CMapCache_New
 *
 * @description:
 *   Create a new charmap cache.
 *
 * @input:
 *   manager ::
 *     A handle to the cache manager.
 *
 * @output:
 *   acache ::
 *     A new cache handle.  `NULL` in case of error.
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   Like all other caches, this one will be destroyed with the cache
 *   manager.
 *
 */
FT_EXPORT(FT_Error)
FTC_CMapCache_New(FTC_Manager manager, FTC_CMapCache *acache);

/**************************************************************************
 *
 * @function:
 *   FTC_CMapCache_Lookup
 *
 * @description:
 *   Translate a character code into a glyph index, using the charmap
 *   cache.
 *
 * @input:
 *   cache ::
 *     A charmap cache handle.
 *
 *   face_id ::
 *     The source face ID.
 *
 *   cmap_index ::
 *     The index of the charmap in the source face.  Any negative value
 *     means to use the cache @FT_Face's default charmap.
 *
 *   char_code ::
 *     The character code (in the corresponding charmap).
 *
 * @return:
 *    Glyph index.  0~means 'no glyph'.
 *
 */
FT_EXPORT(FT_UInt)
FTC_CMapCache_Lookup(FTC_CMapCache cache, FTC_FaceID face_id, FT_Int cmap_index,
                     FT_UInt32 char_code);

/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*****                                                               *****/
/*****                       IMAGE CACHE OBJECT                      *****/
/*****                                                               *****/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/

/**************************************************************************
 *
 * @struct:
 *   FTC_ImageTypeRec
 *
 * @description:
 *   A structure used to model the type of images in a glyph cache.
 *
 * @fields:
 *   face_id ::
 *     The face ID.
 *
 *   width ::
 *     The width in pixels.
 *
 *   height ::
 *     The height in pixels.
 *
 *   flags ::
 *     The load flags, as in @FT_Load_Glyph.
 *
 */
typedef struct FTC_ImageTypeRec_ {
	FTC_FaceID face_id;
	FT_UInt width;
	FT_UInt height;
	FT_Int32 flags;

} FTC_ImageTypeRec;

/**************************************************************************
 *
 * @type:
 *   FTC_ImageType
 *
 * @description:
 *   A handle to an @FTC_ImageTypeRec structure.
 *
 */
typedef struct FTC_ImageTypeRec_ *FTC_ImageType;

/* */

#define FTC_IMAGE_TYPE_COMPARE(d1, d2)                                                             \
	((d1)->face_id == (d2)->face_id && (d1)->width == (d2)->width && (d1)->flags == (d2)->flags)

/**************************************************************************
 *
 * @type:
 *   FTC_ImageCache
 *
 * @description:
 *   A handle to a glyph image cache object.  They are designed to hold
 *   many distinct glyph images while not exceeding a certain memory
 *   threshold.
 */
typedef struct FTC_ImageCacheRec_ *FTC_ImageCache;

/**************************************************************************
 *
 * @function:
 *   FTC_ImageCache_New
 *
 * @description:
 *   Create a new glyph image cache.
 *
 * @input:
 *   manager ::
 *     The parent manager for the image cache.
 *
 * @output:
 *   acache ::
 *     A handle to the new glyph image cache object.
 *
 * @return:
 *   FreeType error code.  0~means success.
 */
FT_EXPORT(FT_Error)
FTC_ImageCache_New(FTC_Manager manager, FTC_ImageCache *acache);

/**************************************************************************
 *
 * @function:
 *   FTC_ImageCache_Lookup
 *
 * @description:
 *   Retrieve a given glyph image from a glyph image cache.
 *
 * @input:
 *   cache ::
 *     A handle to the source glyph image cache.
 *
 *   type ::
 *     A pointer to a glyph image type descriptor.
 *
 *   gindex ::
 *     The glyph index to retrieve.
 *
 * @output:
 *   aglyph ::
 *     The corresponding @FT_Glyph object.  0~in case of failure.
 *
 *   anode ::
 *     Used to return the address of the corresponding cache node after
 *     incrementing its reference count (see note below).
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   The returned glyph is owned and managed by the glyph image cache.
 *   Never try to transform or discard it manually!  You can however create
 *   a copy with @FT_Glyph_Copy and modify the new one.
 *
 *   If `anode` is _not_ `NULL`, it receives the address of the cache node
 *   containing the glyph image, after increasing its reference count.
 *   This ensures that the node (as well as the @FT_Glyph) will always be
 *   kept in the cache until you call @FTC_Node_Unref to 'release' it.
 *
 *   If `anode` is `NULL`, the cache node is left unchanged, which means
 *   that the @FT_Glyph could be flushed out of the cache on the next call
 *   to one of the caching sub-system APIs.  Don't assume that it is
 *   persistent!
 */
FT_EXPORT(FT_Error)
FTC_ImageCache_Lookup(FTC_ImageCache cache, FTC_ImageType type, FT_UInt gindex, FT_Glyph *aglyph,
                      FTC_Node *anode);

/**************************************************************************
 *
 * @function:
 *   FTC_ImageCache_LookupScaler
 *
 * @description:
 *   A variant of @FTC_ImageCache_Lookup that uses an @FTC_ScalerRec to
 *   specify the face ID and its size.
 *
 * @input:
 *   cache ::
 *     A handle to the source glyph image cache.
 *
 *   scaler ::
 *     A pointer to a scaler descriptor.
 *
 *   load_flags ::
 *     The corresponding load flags.
 *
 *   gindex ::
 *     The glyph index to retrieve.
 *
 * @output:
 *   aglyph ::
 *     The corresponding @FT_Glyph object.  0~in case of failure.
 *
 *   anode ::
 *     Used to return the address of the corresponding cache node after
 *     incrementing its reference count (see note below).
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   The returned glyph is owned and managed by the glyph image cache.
 *   Never try to transform or discard it manually!  You can however create
 *   a copy with @FT_Glyph_Copy and modify the new one.
 *
 *   If `anode` is _not_ `NULL`, it receives the address of the cache node
 *   containing the glyph image, after increasing its reference count.
 *   This ensures that the node (as well as the @FT_Glyph) will always be
 *   kept in the cache until you call @FTC_Node_Unref to 'release' it.
 *
 *   If `anode` is `NULL`, the cache node is left unchanged, which means
 *   that the @FT_Glyph could be flushed out of the cache on the next call
 *   to one of the caching sub-system APIs.  Don't assume that it is
 *   persistent!
 *
 *   Calls to @FT_Set_Char_Size and friends have no effect on cached
 *   glyphs; you should always use the FreeType cache API instead.
 */
FT_EXPORT(FT_Error)
FTC_ImageCache_LookupScaler(FTC_ImageCache cache, FTC_Scaler scaler, FT_ULong load_flags,
                            FT_UInt gindex, FT_Glyph *aglyph, FTC_Node *anode);

/**************************************************************************
 *
 * @type:
 *   FTC_SBit
 *
 * @description:
 *   A handle to a small bitmap descriptor.  See the @FTC_SBitRec structure
 *   for details.
 */
typedef struct FTC_SBitRec_ *FTC_SBit;

/**************************************************************************
 *
 * @struct:
 *   FTC_SBitRec
 *
 * @description:
 *   A very compact structure used to describe a small glyph bitmap.
 *
 * @fields:
 *   width ::
 *     The bitmap width in pixels.
 *
 *   height ::
 *     The bitmap height in pixels.
 *
 *   left ::
 *     The horizontal distance from the pen position to the left bitmap
 *     border (a.k.a. 'left side bearing', or 'lsb').
 *
 *   top ::
 *     The vertical distance from the pen position (on the baseline) to the
 *     upper bitmap border (a.k.a. 'top side bearing').  The distance is
 *     positive for upwards y~coordinates.
 *
 *   format ::
 *     The format of the glyph bitmap (monochrome or gray).
 *
 *   max_grays ::
 *     Maximum gray level value (in the range 1 to~255).
 *
 *   pitch ::
 *     The number of bytes per bitmap line.  May be positive or negative.
 *
 *   xadvance ::
 *     The horizontal advance width in pixels.
 *
 *   yadvance ::
 *     The vertical advance height in pixels.
 *
 *   buffer ::
 *     A pointer to the bitmap pixels.
 */
typedef struct FTC_SBitRec_ {
	FT_Byte width;
	FT_Byte height;
	FT_Char left;
	FT_Char top;

	FT_Byte format;
	FT_Byte max_grays;
	FT_Short pitch;
	FT_Char xadvance;
	FT_Char yadvance;

	FT_Byte *buffer;

} FTC_SBitRec;

/**************************************************************************
 *
 * @type:
 *   FTC_SBitCache
 *
 * @description:
 *   A handle to a small bitmap cache.  These are special cache objects
 *   used to store small glyph bitmaps (and anti-aliased pixmaps) in a much
 *   more efficient way than the traditional glyph image cache implemented
 *   by @FTC_ImageCache.
 */
typedef struct FTC_SBitCacheRec_ *FTC_SBitCache;

/**************************************************************************
 *
 * @function:
 *   FTC_SBitCache_New
 *
 * @description:
 *   Create a new cache to store small glyph bitmaps.
 *
 * @input:
 *   manager ::
 *     A handle to the source cache manager.
 *
 * @output:
 *   acache ::
 *     A handle to the new sbit cache.  `NULL` in case of error.
 *
 * @return:
 *   FreeType error code.  0~means success.
 */
FT_EXPORT(FT_Error)
FTC_SBitCache_New(FTC_Manager manager, FTC_SBitCache *acache);

/**************************************************************************
 *
 * @function:
 *   FTC_SBitCache_Lookup
 *
 * @description:
 *   Look up a given small glyph bitmap in a given sbit cache and 'lock' it
 *   to prevent its flushing from the cache until needed.
 *
 * @input:
 *   cache ::
 *     A handle to the source sbit cache.
 *
 *   type ::
 *     A pointer to the glyph image type descriptor.
 *
 *   gindex ::
 *     The glyph index.
 *
 * @output:
 *   sbit ::
 *     A handle to a small bitmap descriptor.
 *
 *   anode ::
 *     Used to return the address of the corresponding cache node after
 *     incrementing its reference count (see note below).
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   The small bitmap descriptor and its bit buffer are owned by the cache
 *   and should never be freed by the application.  They might as well
 *   disappear from memory on the next cache lookup, so don't treat them as
 *   persistent data.
 *
 *   The descriptor's `buffer` field is set to~0 to indicate a missing
 *   glyph bitmap.
 *
 *   If `anode` is _not_ `NULL`, it receives the address of the cache node
 *   containing the bitmap, after increasing its reference count.  This
 *   ensures that the node (as well as the image) will always be kept in
 *   the cache until you call @FTC_Node_Unref to 'release' it.
 *
 *   If `anode` is `NULL`, the cache node is left unchanged, which means
 *   that the bitmap could be flushed out of the cache on the next call to
 *   one of the caching sub-system APIs.  Don't assume that it is
 *   persistent!
 */
FT_EXPORT(FT_Error)
FTC_SBitCache_Lookup(FTC_SBitCache cache, FTC_ImageType type, FT_UInt gindex, FTC_SBit *sbit,
                     FTC_Node *anode);

/**************************************************************************
 *
 * @function:
 *   FTC_SBitCache_LookupScaler
 *
 * @description:
 *   A variant of @FTC_SBitCache_Lookup that uses an @FTC_ScalerRec to
 *   specify the face ID and its size.
 *
 * @input:
 *   cache ::
 *     A handle to the source sbit cache.
 *
 *   scaler ::
 *     A pointer to the scaler descriptor.
 *
 *   load_flags ::
 *     The corresponding load flags.
 *
 *   gindex ::
 *     The glyph index.
 *
 * @output:
 *   sbit ::
 *     A handle to a small bitmap descriptor.
 *
 *   anode ::
 *     Used to return the address of the corresponding cache node after
 *     incrementing its reference count (see note below).
 *
 * @return:
 *   FreeType error code.  0~means success.
 *
 * @note:
 *   The small bitmap descriptor and its bit buffer are owned by the cache
 *   and should never be freed by the application.  They might as well
 *   disappear from memory on the next cache lookup, so don't treat them as
 *   persistent data.
 *
 *   The descriptor's `buffer` field is set to~0 to indicate a missing
 *   glyph bitmap.
 *
 *   If `anode` is _not_ `NULL`, it receives the address of the cache node
 *   containing the bitmap, after increasing its reference count.  This
 *   ensures that the node (as well as the image) will always be kept in
 *   the cache until you call @FTC_Node_Unref to 'release' it.
 *
 *   If `anode` is `NULL`, the cache node is left unchanged, which means
 *   that the bitmap could be flushed out of the cache on the next call to
 *   one of the caching sub-system APIs.  Don't assume that it is
 *   persistent!
 */
FT_EXPORT(FT_Error)
FTC_SBitCache_LookupScaler(FTC_SBitCache cache, FTC_Scaler scaler, FT_ULong load_flags,
                           FT_UInt gindex, FTC_SBit *sbit, FTC_Node *anode);

/* */

FT_END_HEADER

#endif /* FTCACHE_H_ */

/* END */
